1. Field of the Invention:
The present invention relates to fuel injection pumps for diesel engines, and more particularly to a fuel injection pump having a pre-stroke adjusting mechanism.
2. Prior Art:
A typical example of fuel injection pump with a pre-stroke adjusting mechanism is disclosed in Japanese Utility Model Laid-open Publication No. 59-52175. As shown in FIG. 5 of the accompanying drawings, the disclosed fuel injection pump comprises a pump body 1 including a plunger barrel 3 secured thereto and a plunger 4 slidably disposed in the plunger barrel 3 and reciprocably movable in response to rotation of an engine crankshaft (not shown). The plunger 4 includes a fuel intake and discharge hole 24 defined in a portion thereof facing a fuel collecting chamber or sump 18. A control sleeve 17 is slidably fitted over the plunger 4 above the hole 24, and a control rod 29 extends normal to the axis of the control sleeve 17. A ring 41 is fitted over the control rod 29 and secured thereto by a screw 42. An engagement element 36 is secured to the ring 42 and projects radially outwardly therefrom into an engagement groove 22 in the control sleeve 17. With this arrangement, the control rod 29 is turned to angularly move the engagement element 36 whereupon the control sleeve 17 moves axially upwardly or downwardly, thereby changing its axial position with respect to the plunger 4. Thus, the distance between the control sleeve 17 and the fuel intake and discharge hole 24, i.e. the plunger pre-stroke can be regulated by turning the control rod 29 to appropriate positions.
As described above, the engagement element 36 of the known fuel injection pump is secured to the ring 41 which is in turn fitted over the control rod 29. With this construction, the diameter of the control rod 29 and the width of the ring 41 must be large enough to withstand mechanical forces applied thereto with the result that a joint portion between the control sleeve 17 and the control rod 29 is likely to become large in size. With this largeness of the joint portion, couplings 43, 44 must be detached when the control sleeve 17 and the control rod 29 are to be joined together. Then the ring 41 with the engagement element 36 mounted thereon is placed in the fuel collecting chamber 18 to bring the engagement element 36 into engagement with the engagement groove 22 in the conrtol sleeve 17. While holding the ring 41 in this position, the control rod 29 is inserted into the pump body 1 and is then fitted into the ring 41. The foregoing steps of operation must be repeated until the coupling between the control sleeve 17 and the control rod 29 is completed for all of the engine cylinders so that a simple assembling of the fuel injection pump is difficult to achieve.